Differential responses of ecosystem respiration components to experimental warming in a meadow grassland on the Tibetan Plateau

Global warming is anticipated to have profound effects on terrestrial carbon fluxes and thus feed backs to future climate change. Ecosystem respiration (R-eco) is one of the dominant components of biosphere CO2 fluxes, but the effects of warming on Reco are still unclear. A field warming experiment using open top chambers (OTCs) was conducted in a meadow grassland on the Tibetan Plateau to study the effects of warming on the components of Reco. Warming significantly enhanced above-ground plant respiration (R-agb) and total autotrophic plant respiration (R-plant 1 by 28.7% and 19.9%, respectively, but reduced heterotrophic respiration (R-h) by 10.4%. These different responses resulted in the insensitive responses of Reco and soil respiration (R-s) to the experimental warming. The warming treatment also increased R-plant/R-eco and R-agb/R-eco. by 8.4% and 17.3%, respectively, while decreasing R-h/R-eco, by 19.0%, suggesting that warming could eventually cause R-eco to be dominated by R-plant. Enhancements in Roam and R-agb were related to the warming-induced increases in aboveground biomass (AGB) while reduced R-h was closely coupled with warming-induced decrease of microbial biomass carbon. Our results highlight that the differential responses of the components of R-eco to different environmental physics under warming scenarios should be taken into consideration to project the future carbon-climate feed backs. (C) 2016 Elsevier B.V. All rights reserved